In February 1952, the Air Force announced its plans to build Grand Forks Air Force Base to support Strategic Air Command bombers and tankers as well as Air Defense Command fighter-interceptors. On February 8, 1957, Air Defense Command activated the 486th Fighter Group on Grand Forks Air Force Base. In December 1957, the Air Force activated the Grand Forks Air Defense System of the North American Air Defense Command. This sector became operational with the Semi-Automatic Ground Environment system to cover the air space of North Dakota, South Dakota, and Minnesota and one Canadian province (Manitoba). The first Boeing B-52H Stratofortress arrived on April 29, 1962. In 1983, the B-52Hs were replaced with B-52Gs, and on December 4, 1986, B-52Gs departed the base, replaced by B-1B Lancers in 1987. The 321st Strategic Missile Wing became operational to administrate, man, and operate the Minuteman II intercontinental ballistic missiles (ICBMs) in December 1966. The Air Force made the formal announcement that it would remove 150 Minuteman III ICBMs with the inactivation of the 321st on July 2, 1998. After that, the Detachment 1, 9th Reconnaissance Wing arrived with the Global Hawk.